“It’s like pouring money into the ground,” said Godfrey the builder as we stood watching gallons of ready mix concrete swirl around the foundation trenches. It was a particularly poignant observation because the money at stake was mine, as I’d opted to fund all the materials directly.
This was the fifth and final truckload, totalling an impressive 28m3 — sufficient for a sizeable self build house. Luckily, Godfrey managed to call in a few favours with the concrete supplier and negotiate a significantly lower price per m3 (£79 + VAT) than I’d been quoted.
Ready for Inspection
I was mightily relieved to have reached the concreting stage without any major setbacks. Things hadn’t looked so rosy the day before as our freshly dug trenches began to rapidly fill with water a couple of hours before building control were due to carry out their first inspection.
There was just enough time to race over to the nearest tool-hire store and grab an industrial-sized pump, sufficient to suck a 2ft depth of water out of harm’s way. As Andrew, the local authority building control officer, arrived on site, the trench bottoms appeared pleasingly smooth, level and innocent of all but the faintest sheen of moisture, flanked by sufficiently firm sides ruling out the need for temporary shoring.
After 15 minutes of questions, Andrew seemed generally satisfied (save for commenting on the lack of hi-vis jackets on site), casually announcing: “You’re OK to carry on.” This was music to our ears.
Before drawing a line under a successful inspection, it’s advisable to check when building control want to visit next — in this case, at the beam and block floor stage the following week. I made a note to call them in good time.
Pouring the Concrete
Ordering concrete before you’ve got the all-clear from building control is risky — quantities may need to be changed or foundation designs radically modified at the last minute. But it’s even more risky leaving freshly excavated trenches exposed for too long without support from timber shoring.
This was particularly the case on our site as clay is prone to rapid drying, shrinking and cracking with a consequent risk of collapse. (Serious injuries from trench implosion, even fatalities, still unfortunately occur on poorly managed sites.)
This is where a little local influence can come in handy, and as a long-established building contractor Godfrey managed to pull a few strings to get a convoy of concrete wagons mobilised the following afternoon, rather than the more usual three to five days’ notice.
I needed to start placing orders for building materials, allowing a couple of days’ notice for deliveries of Portland cement, soft building sand (seven tonnes) plus packs of engineering bricks and blocks for the lower walls, not forgetting to chase up the ground floor beams on order.
An often-overlooked cost on restricted access sites is a pump to propel the concrete mix to its destination via long hoses, which can add a fair amount of expense (typically £300 or more). There were two ways we could avoid this extra cost. Godfrey’s son Daniel (second in command on site) turned up with a dumper truck to barrow it in from the trucks in the lane if necessary. But what we ideally wanted was for the cement wagons to reverse up and dump their loads directly into the trenches, but it was by no means clear that this was doable.
The narrow lane outside is bounded by a perilously close stream on the far side, making it extremely tight for the wagons to turn sharply and reverse up a fairly steep slope. And to make matters more difficult the loose topping of granular sub-base would most likely see fully laden truck wheels struggling for grip when subjected to several tonnes of duress.
As it turned out, thanks to some deft driving, the revving wagons made their way one by one up the slope undeterred by unsettling flurries of wheel spin, delivering their payloads right on target.